Floatable oil absorber

ABSTRACT

A floatable modular device for absorbing oil from a surface, includes a generally disk-shaped floatable cage tapering towards the periphery of the cage in a peripheral region thereof; and a water-repellent strip- or chip-shaped oil absorbent accommodated in the cage, wherein the cage further includes at least one connector, element configured for joining plural ones of the modular devices together, to form an articulate oil absorber in which the individual cages are oriented in parallel to one another. A method of manufacturing the device includes providing a first, grid-like sheet made of plastics, positioning a water-repellent strip- or chip-shaped oil absorbent on the first grid-like sheet, positioning a second sheet on the oil absorbent, and welding the first and second sheets together at their peripheries, with the oil absorbent in between, wherein peripheral regions of the first and second sheets are bent towards one another.

The present invention relates to certain floatable devices for absorbingspilt oil from a surface, in particular a water surface. It also relatesto the use of the floatable devices for absorbing spilt oil and to amethod of manufacturing such floatable devices. It further relates to anabsorber material.

It is well known that during marine oil well drilling, oil production,and oil transportation operations the possibility exists for oil to bespilt, which will then float as a film on the water, being subject todrifts and currents which may eventually wash the spilt oil or a lessvolatile part of it ashore.

Previous proposals to deal with spilt oil on beach or water surfacesinclude so-called booms, i.e., floatable tube-like structures having anoil absorbing material disposed near their circumference (e.g., WO93/04236 A1). Such booms have primarily a barrier effect, in that theyseparate the contaminated water surface from clean areas; their supposedsecondary effect is to absorb oil coming into contact with the booms. Inactual practice, the efficacy of known booms is unsatisfactory, however.

It is also known in principle, to drop hydrophobic mats onto oilcontaminated water or other surfaces, and to recollect such mats aftersome time (e.g., U.S. Pat. No. 6,506,307 B1). Again, in actual practice,it has become clear that it is quite ineffective to deal even with amedium-sized marine oil spill in this manner.

It is an object of the present invention to suggest a product, a device,its uses, and its method of manufacture, with which the detrimentaleffects of marine oil spills can be reduced in a more effective manner.This is accomplished by the product, the devices, the method ofmanufacture, and the uses of present invention as follows:

According to a first aspect, a fibrous oil-absorbing material is cut asstrips or chips from a melt-blown polyolefin master web. The strips aregenerally several centimeters in length, several millimeters in width,and around 1-3 millimeters in thickness (wherein “length” exceeds“thickness”, and “width” is neither more than length nor less thanthickness). As the melt-blown web comprises the water-repellentpolyolefin fibers in an entangled fashion, the strips or chips will notallow water to enter between the fibers when disposed on a water surfaceor when immersed in water. By contrast, any oil coming into contact withthe strips or chips will displace the air present between the fibers,and will be absorbed by the strips/chips, thereby considerably reducingthe overall buoyancy of the oil absorbent material, but still floatingon water. According to embodiments, polyethylene, polypropylene ormixtures of these are employed. The aspect ratio (length divided bycircular equivalent cross-sectional diameter) may be between 10 and 1000(or 100), and the circularity (smallest diameter divided by largestdiameter of some cross-section) is in embodiments between 0.1 and 0.99,between 0.2 and 0.95, or between 0.4 and 0.7.

According to a second aspect, a device for absorbing oil from a surfaceis modular and floatable, and comprises a generally disk-shapedfloatable cage tapering towards the periphery of the cage in aperipheral region thereof, and a water-repellent oil absorbent shaped asstrips or chips accommodated in the cage. The cage further comprises atleast one, e.g. two or four to eight connector elements configured forjoining plural ones of the modular devices together, to form anarticulate oil absorber in which the individual cages are oriented inparallel to one another. The outward tapering is present on the entireperiphery or on only part, but at least on half or more than half of it.

In embodiments, the at least one connector element includes connectingstructure configured to support the plural ones of the cages in anon-coplanar, face-on manner as a stack, in which stack the peripheralregions of the mutually adjacent cages form a corrugated envelope. Inone example, each cage may have a central eye, and all cages arearranged on a common rod or tube passing through the eyes. The cages maybe round, or generally polygonal.

In embodiments, a stack of mutually connected devices results, whereinthe stack may include connecting structure configured to connect a topor bottom of the stack to the top or bottom of an adjacent, like stackin an end-on fashion. In this manner, a chain of stacks can be formed,each stack constituting a member of the chain. In some embodiments, acushion may be interposed between the connected stacks. E.g., a smallernumber of disks than the number accommodated in each stack may bearranged between adjacent stacks, to form such a cushion, allowing somerelative bending of the connected stacks.

In another embodiment, there are plural connector elements on eachmodular device, each configured to be joined with a correspondingconnector element of an adjacent, like modular device in a coplanar,edge-on fashion, to form a one- or two-dimensional array, in which arrayeach modular device has a generally polygonal disk shape, such asrectangular or square. The correspondence of the connectors may be oneof a male/female relation. The forming of a two-dimensional array may beachieved by orienting the corresponding connectors in two transversedirections, such as extending from adjacent edges.

In this embodiment, each modular device takes the shape of a mat, withplural connectors arranged around its periphery. E.g., the rims may befolded in the region where the connectors are attached to provideenhanced stability. Neighboring mats can then be connected bycorresponding connectors such as ones made of a plastic material, toform an array of mats matching e.g. the size of the oil spill. Thematching connectors may be arranged radially outward, or in someembodiments, lengthwise on the circumferential rim sufficiently close tothe nearest corner that the interlocking portion of one of theconnectors (e.g. the male part) extends beyond the corner, while itsmatching (female) counterpart on the adjacent mat extends almost up tothe corner. It is contemplated that on a square mat, there are four maleconnectors arranged in a handed fashion, e.g. all of them on leftmost(or alternatively, rightmost) ends of each edge and four femaleconnectors arranged on rightmost (or leftmost, respectively) corners. Inthis manner, adjacent mats always fit. In some other embodiments, themale and female connectors are distributed in some other orderlyfashion, potentially requiring some rotating of mats to make adjacentones fit each other.

In an embodiment, a stack of mutually connected modular devices of thissort is formed before actual use, wherein connected adjacent ones of thegenerally polygonal modular devices are folded upon one another in adirection transverse to the plane of the modular devices. Usually, thedevices are placed horizontally, and stacked vertically. Naturally, sucha stack may also be disposed horizontally, with the individual modulesarranged vertically. In a related embodiment, corresponding mats inseveral (e.g., 2-4, or 3) adjacent stacks are also interconnected. Inthis manner, the interconnected stacks may be unfolded to yield atwo-dimensional mat array. Depending on the size of the mats, threeinterconnected stacks have a length extension fitting into a standard20′ or 40′ container (widthwise). In this (or other) manner, about2000-2500 mats fit into one standard 20′ container; or about 4000-6000mats in one standard 40′ container, and are ready for being used.

The stability of the individual modules may in some embodiments beenhanced by providing, in a central region thereof, a direct connectionbetween the opposing grid faces, such as pointwise, or in a pair ofclosely neighboring, yet spaced-apart points, or a short length betweensuch points, or even a circular connecting feature having an openingoperable to receive a connecting rod or rope.

According to another aspect, a method of manufacturing a floatablemodular device for absorbing oil from a surface comprises providing afirst, grid-like sheet made of plastics, positioning a water-repellentstrip-shaped oil absorbent on the first grid-like sheet, positioning asecond sheet on the oil absorbent, and then welding the first and secondsheets together at their peripheries, with the oil absorbent in between,wherein peripheral regions of the first and second sheets are benttowards one another. Depending on which device is to be manufactured,the sheets may be round (circular or oval) or polygonal (such as squareor hexagonal). Both sheets may be grid-like, or else only one of them,the other being oil-impervious, for certain on-shore applications. Thegrid-like sheet is water-permeable and also oil-permeable.

According to a further aspect, the stack of mutually connected modulardevices may be used for absorbing oil spilt on a water surface,comprising connecting plural ones of the stacks as a chain and disposingthe chain onto a part of the water surface in a vicinity of the part ofthe water surface on which the oil has been spilt. In embodiments, theoil has a drift direction, and the chain is disposed transverse to thedrift direction, wherein the stacks are oriented such that theindividual cages are oriented such that their thickness directionsextend transverse to the drift direction of the spilt oil. In thismanner, the chain may serve as a barrier to the oil, while the water mayflow relatively freely through the vertically arranged cages, in thisway enhancing the amount of oil absorbed as compared to a structurewhich also blocks the flow of water. The drift direction may result froma radial motion of the oil away from the source of the spill, and/or alinear motion due to a current or wind action. Usually, near a coastlinethe drift direction is transverse to the coastline, eventually washingspilt oil ashore.

According to a yet further aspect, a stack of mats is used for absorbingoil spilt on a water or coastline surface, comprising unfolding thestack and disposing the mats as a one-dimensional or two-dimensionalinterconnected flat array onto the spilt oil or onto a coastline area tobe protected from the spilt oil. In the former case, each modular devicemay have two cage faces made of grid-like sheets, such that the oilabsorber is accessible to the oil from both faces, and the stack is usedon a water surface on which oil has been spilt. In this manner, both oilfrom underneath and oil sprayed on the top surface by wave and windaction can be absorbed. In the latter case, each modular device has onecage face made of a grid-like sheet, the opposing cage face made of anoil-impervious sheet, such that the oil absorber is accessible to theoil from only one face, and the stack is used on a coastline surface onwhich no oil has yet been spilt, with the oil-impervious face down andthe grid-like face up so as to protect the coastline surface from oil tobe washed ashore.

In embodiments, the absorbent material and/or shape and/or the number ofcages per stack is selected in dependence of the oil grade. E.g., moreviscous oil may call for fewer disks per stack, and/or less absorbentper module, and vice versa. Additionally or alternatively, the ambienttemperature when used may be employed to select the absorbent material.

In further embodiments, the disposed modular devices are laterrecollected along with the absorbed oil. Furthermore, the modular devicemay be burnt together with the absorbed oil so as to release thermalenergy, and a part of the thermal energy so released may be convertedinto electrical or mechanical energy.

The invention will now be described with respect to the accompanyingdrawings:

FIG. 1 shows a stacked-disks module according to a first embodiment;

FIG. 2 shows an end-on view of the module of FIG. 1;

FIG. 3 shows a module according to a second embodiment;

FIG. 4 shows a variant of the second embodiment with plural connectors;

FIG. 5a,b shows interconnected modules of the first and secondembodiments, from above and in cross-section; and

FIG. 6a,b show another variant of the second embodiment (6 a) for usetogether with a dragging cable (6 b).

According to the first embodiment of FIG. 1, a number of 15-25individual disks 3 is stacked on a common center rod or tube 5, to forma generally cylindrical module 1. The stack is held together by endgrids 7, which end grids are in turn connected by a number of 3-8 outertubes 17 (in the example, 5 tubes are shown). The end grids 7 may have astar shape as shown (with 5 radial struts 19, one of which is showndashed). The end grids may be made of a solid, hollow, or porous plasticmaterial. The center tube may be replaced by a rope tightened betweenthe end grids, which in turn may be replaced by disks or concentricrings.

With respect to FIG. 2, each individual disk 3 is round in shape anddoughnut-shaped in cross section, having an outer peripheral region inwhich the thickness gradually tapers towards the rim. Each disk hasfaces made of grid-like polyethylene sheets, and an interior made up ofpolypropylene (and/or polyethylene) non-woven (such as melt-blown) webstrips 50′. The polyethylene grids may have a weight of 300-400 g/m²,with openings of 3-10 mm mean size, and/or 5-12 mm pitch; or 5-8 mm meansize and/or 7-10 mm pitch. The strips 50′ may be 40-120 mm or 70-100 mmin length, 3-5 mm in width, and 0.5-2 mm in thickness. The length may befrom 12 cm down to 7 cm, or still less than 7 cm down to 4 cm or evendown to 1 cm. The width may be less than 3 mm down to 2 mm; or more than5 mm up to 25 mm, or even more than 25 mm up to 50 mm (particularly ifchip-shaped). The thickness may be more than 1 mm and up to 2 mm, orstill more than 2 mm up to 5 mm. In some applications, the thickness maybe less than 1 mm down to 0.5 mm. Generally, the width/thickness ratiois in the range 1.5-10, with 3-5 preferred. In one variant, thenon-woven polyolefin material is relatively thin, having an area weightof about 120 to 240 g/cm² and is cut into elongated strips, the aspectratio (length divided by equivalent diameter, i.e. the diameter of acircle having the same area as the cross-section) of which is more than5 or even 8. The circularity (the ratio of the minimum diameter to themaximum diameter at some cross-section; equals 1 for a cylinder) of suchstrips may be in the range of 0.2 to 0.95. In another variant, a thickernon-woven polyolefin material having an area weight of more than 240 to480 g/cm² is cut into polygonal, pointed chips 50 of a generally oblateshape. In this case, the ratio of the equivalent diameter of the chips50 to their thickness (“platyness”) is at least 5, or more than 8. Itseems that such polygonal, in particular trigonal or quadrigonal chipstend to form large spaces between each other, into which spaces watercan flow and can transport any oil to the absorbing chips. For this tooccur, it is desirable if at least two corners of each chip have anglesof not more than 100°, or less than 75°. Suitable shapes aresubstantially equilateral triangles, trapezoidals, parallelograms,diamond shapes, squares and rectangles. If pentagons, hexagons or higherpolygons are employed, it is preferred that irregular or non-regularshapes with at least two acute angles are chosen.

While the size D of the disks depends on the intended use, it has beenfound that 30-100 cm is most useful, with 40-70 cm preferred. Theoverall diameter D′ of the module will be slightly larger, by about 5 to10 cm. The strip-shaped (or chip-shaped) absorber material (250-350 gfor a 50-60 cm sized disk) allows for a loose packing avoiding denseclots. Therefore, water may pass relatively unrestrictedly through thebulk of the module, the created turbulence carrying the oil to theabsorber. Around the central opening, the front and back grids may bewelded together, or connected by some connecting structure as e.g. aplastic bushing, or in embodiments can be left unconnected if the sizeof the opening sufficiently closely matches the outer diameter of therod, tube or rope inserted into it so that the absorbent strips (orchips) cannot pass through any gap formed.

The method of manufacturing the individual disks includes placing asuitable amount of the oil absorbent polypropylene (and/or polyethylene)strips (or chips) onto a lower grid-like polyethylene sheet, thenplacing a like sheet on top, and welding the sheets together at theirperipheral rims 21. The amount of the strips is such that a centerthickness of each disk is about 2 to 5 cm. In some embodiments, thecentral opening is then punched with or without forming a weld or otherconnection between the upper and lower grids. In other embodiments, thecentral openings are formed before the welding together of the grids, orat the same time.

In the embodiment shown in FIG. 1, 25 disks are housed inside eachmodule 1, with 5 further disks 15 mounted on an outward extension of thecenter rod 5, held by an end disk 9 of the rod. Two cables 11(polypropylene) with hooks 13 are led through two (non-adjacent ones) ofthe 5 outer tubes 17, for connecting adjacent modules 1 to one another.In the connected state, the 5 external disks 15 fill the space betweenadjacent modules 1. In this manner, a chain of modules 1 can be disposedtransverse to the expected drift of spilt oil, the oil everywhereencountering an oil absorbing module 1. A typical size of a module wouldbe 0.5 m to 1 m in length L including the 10-20 cm extension L″ for theouter disks 15 (length of main body L′=L−L″).

Each module of this type can absorb more than 100 l and up to 150 l ofoil, e.g. 110-120 liters for a module 60 cm in diameter and 75 cm inlength, weighing only 12 kg dry. It may be noted that on account of thelow density of the plastic material of 950-965 kg/m³ and the airentrapped between the fibers the inventive structures have sufficientbuoyancy to float even in fresh water, more so in salt water. The bulkof the structures will, however, gradually sink below sea level as oilis absorbed and entrapped air is displaced, and therefore is able tocontinue absorbing oil from the water passing through it, while no oilcan pass through underneath the modules.

In the second embodiment of FIG. 3, a generally rectangular or squaremat 10 is shown, with top and bottom sheets of the same grid-likepolyethylene material as described above, and also the same filling ofoil absorbing polypropylene strips. In this example, the rims of thepillow are folded (indicated by dashed lines), and eyes 22 (circular oroval as shown) formed therethrough to provide connectability. Weldingthe rims may be dispensable where the eyes 22 are configured to securethe rims against unintended reopening. Folding the rims may also bedispensable where the weld connection is sufficiently sturdy in itself,or is enhanced by connectors attached to the unfolded rims. Suchconnectors are described below.

Such mats 10, the size of which may vary e.g. between 50 cm and 100 cmside length, can easily be interconnected to form a two-dimensionalarray of in principle unlimited size. In one approach, suchinterconnected mats are folded atop one another in the shape of a stack,ready to be unfolded when used. In this manner, it is possible toquickly dispose large numbers of mats onto an oil-contaminated watersurface or beach area, while still being able to later recollect theoil-filled mats as easily. Each mat of this type, containing about 2kg/m² of absorbing material, may absorb more than 10 l and up to 20 l ofoil, e.g. 16 l per m².

In the embodiment of FIG. 4, there are two connectors (male 23′ and/orfemale 23″) on each side of a polygonal mat 20, for providing aconnection across the edge. In one example, one (male) connector 23′extends beyond the edge, and one corresponding (female) connector 23″extends only almost up to the edge of the mat 20. In another example,there are two or three male connectors on each one of opposing edges,and two or three female connectors on the other opposing edges. Otherregular arrangements are also possible. In the embodiment shown, theperipheral parts 25′ are welded together, the central region 25″ beingstuffed with the absorbing material strips or chips described above, ina non-ordered and non-compressed fashion, so that large interstices aredeliberately formed between the strips (or chips). Bending of the stripsis desirable, as long as the strips entangle each other. In theembodiment shown, there is also a central loop 27 formed through holes29 in the bottom sheet and through the top grid, in order to provideenhanced stability and keep the absorber filling (in area 25″) in placeduring handling of the mat 20.

It is also contemplated to use mats of this type together with themodules, in order to absorb the spilt oil when it has accumulated upwind(or upstream) of a chain of the modules of the invention. In a variant,the mats are connected downstream (or downwind) of the chain of modulesto absorb any oil passing by (or under, or over, or through) the chain,as in FIG. 5. The modules 1 a are individually connected to mats 20 a,and are also interconnected by e.g. hooks 29′ and rope loops 29″. Inorder to provide this connectability, matching (corresponding)connectors 23 a are not only provided on the mats 20 a, but also on themodules 1 a. Although not all the connectors are shown on the mats 20 ain this drawing, the skilled person will understand that plural rows ofmats 20 a may be employed if desired (indicated by dots). In FIG. 5a ,which is a top view, one of the peripheral tubes 11 a is shown dashed,to indicate that it is lowest. In the side view of FIG. 5b , it isindicated that the interconnection of the modules 1 a is provided viatubes 11 a′, e.g. by ropes slipped therethrough, the ropes connectingthe hooks 29′ and loops 29″ shown in FIG. 5a . FIG. 5b also shows asecond row of mats 20 a, connected to the first row of mats 20 a bymatching connectors 23′, 23″. It is evident that due to the higherweight of the rope connection, the modules will rotate until the tubes11 a′ settle near the water level. It is at these points (connection oftubes 11 a′ to the end grids 7 a) where the connectors 23 a are mostsuitably arranged.

In a variant (see also FIG. 4), one of the two faces of each mat is notgrid-shaped, but is made of an oil-impervious sheet. In this embodiment,mats can be placed e.g. on a beach or other coastal area which is notyet contaminated. When spilt oil is later washed ashore by wave and windaction, it will be absorbed by such mats covering the beach, and willnot contaminate the beach. Suitably, each mat has a feature (e.g. aneye) by which it can be fastened to the ground, or a weight can beattached to, so that the waves may not too easily lift the mats, or atleast the row of mats positioned farthest into the water.

The oil-filled modules or mats can be recollected and removed from thewater surface, significantly reducing the amount of oil present on thewater. The modules or mats may be burnt together with the oil, in orderto use the thermal energy so released. In order to provide for cleanburning, no halogenated polymer should be used in the manufacturing ofthe modules and mats, although the use of polyolefins as explained aboveis not always strictly necessary.

The strip-shaped (or chip-shaped) oil absorbent material accommodated inthe cage as described above in some embodiments has the followingstructure: The strips (or chips, respectively) are obtained by cuttingfrom a web-like melt-blown sheet of entangled (non-woven) polypropylene(or polyethylene) fibers. In this manner, the strips or chips are boundto accommodate a substantial volume proportion of air, which is notdisplaced when the strips are put in water because of the hydrophobicityof the fibers and the smallness of the interstices between theindividual fibers. When oil comes into contact with the strips or chips,however, the oil attaches to the fibers' surfaces and displaces theentrapped air. It is quite impossible to wash the adsorbed oil out ofthe strips with water alone and accordingly, the oil remains attached tothe fibers. If desired, the oil-loaded absorber material can thereforebe hauled out of the water together with the enclosing structureaccording to the present invention, and burnt or disposed of. Naturally,any connecting structure may be made of non-halogen-containing resins ormetal. The same holds for ropes and rods used to tie modules together.It may be noted that the polyolefin material should not contain sizeablequantities of surfactant, as any such surfactant (above 2%, or above0.1% by mass) would lower the contact angle of water and could possiblylead to a mere soaking of the fibrous material with water, therebyreducing the oil absorbing property of the material.

During the process of absorbing oil, the buoyancy decreases as entrappedair is gradually displaced by the oil. Nevertheless, the buoyancy, whichinitially is high enough that the most part (one half to two thirds byvolume) of the inventive structures floats above the water level, alwaysremains sufficiently high that at most 80%-95% by volume sink belowwater level, depending to some extent on the type of oil. Furthermore,while initially the lower parts of the structures adsorb oil, during theprocess of adsorbing and, simultaneously, sinking, fresh parts of theabsorber come into contact with the oil until the upper parts of thestructures adsorb the remaining oil. Then, the structures can be removedfrom the water, or replaced with fresh modules.

The generally cylindrical modules according to FIGS. 1 and 2 can be usedas a chain to be disposed around a marine oil spill site, some distanceaway from a coastline to protect the shore from wind drifted oil, oreven across a river in an event where oil has been spilt on an upperpart of the river and, under mainly gravitational forces, flows towardsthe sea. In all of these cases, it is also contemplated to connect, viamatching connecting structure, cylindrical modules of the type of FIGS.1 and 2 with mat-like modules of the type of FIG. 4 (but with a grid onboth sides). For this to be readily done, the modules of FIGS. 1 and 2may be provided with the corresponding male and female fasteners, andmay be made of a matching size with the mats (see FIGS. 5a,b ).

In another embodiment, mats similar to the above described type areformed with one edge being formed into an open-ended pouch 31 (FIGS.6a,b ). In this manner, a dragging (or holding) cable 33 of some lengthcan be used to hold such mats 30 if slipped through the respectivepouches 31. The mats 30 may be interconnected in the above describedmanner. Following the first row of mats, further mats as describedbefore can be connected if required (not shown). The cable 33 can beheld between two vehicles 35 (boats, automobiles, or even helicopters)moving slowly in water, on ice or on a beach, or lowly above either.E.g., in an area where a sizable tidal effect combines with a slopedbeach, the area to be protected from drifting oil may be substantial. Itis then more practical to move a small-sized mat array between two landvehicles at the speed of the moving tide rather than covering the entirebeach with mats.

In order to reduce the friction the cable 33 may cause, it is alsocontemplated to place ball-like rolls 37 between some or all of the mats30. Such balls 37 may be water-tight and may as such also be used asbuoys when the cable/mat-system is used on water surfaces. In FIG. 6a ,the pouches are chamfered 39 so as to provide space for the balls 37 (orrolls). The chamfering may be straight, or concavely curved so as tomatch the outer shape of the ball 37. The inner region 25 a″ of each matis again stuffed with oil adsorbing material, and the outer rim 25 a′ iswelded together on the remaining three sides. In FIG. 6a , theconnectors 23 b′, 23 b″ between adjacent mats 30 are slightly different,in that they are mounted on common fixing points. In FIG. 6b , only thegeneral positioning of the connectors 23 b is indicated. There may bemore connectors for further mat rows.

In arctic or subarctic areas, it is contemplated that such mat arraysare dragged over drift ice or even under drift ice, between two boats orships, to remove spilt oil from on or below the ice, respectively. If amat array is to be dragged under ice, it may be convenient to connectheavier balls between all or some of the mats on the cable, in order toovercome the buoyancy of the mats and bring at least the first row ofmats under the ice. The following mats will then be pressed against theice from below by their inherent buoyancy. Again, the balls between themats will help reducing the friction caused by the cable dragging acrossthe underside of the ice. Naturally, the distance between the draggingships or boats should be adjusted to the cable length and depth of theice.

A similar arrangement of heavier balls between adjacent mats may also besuitable when a mat array on a cable is used on a beach in protectivemanner, so as to keep the first row of mats under the waves and ensurethat any oils carried ashore by the waves is thrown onto the mats fromabove, and not washed underneath.

A similar construction may be held across a river. If necessary, thecable can be additionally held by buoys in the middle of the river, tohelp withstand the dragging forces. In this event, where boat traffic issupposed to occur, there may be two cables in succession, each of whichextends from another bank, with some overlap (as seen along the lengthof the river) in between through which gap the boat traffic is led.Where oil has been spilt on a narrow lake or canal, and both banks areaccessible to land vehicles, it may be more convenient or simply fasterto drag a mat array of the above-described type between two of suchvehicles, along the length of the lake or canal, to gather at least amajor portion of the spilt oil.

In yet another variant, plural mats according to the embodiment of FIG.3 are tied together with one (or two) ropes slipped through one, two ormore of the eyes 22 on one (or two opposing) edges of each mat. If onone rope, the mats are arranged close together, and on a second rope,spaces are left between the mats, the row of mats will form a curve. Byadjusting the intervals suitably, it is possible to form a spiral(Archimedes-type) of mats, which is able to cover a near circular areae.g. on a small lake or pond on which an oil spill has occurred, withaccess to the water from only one spot on the banks. After the oil hasbeen absorbed by the mats, the can be simply recollected in reversefashion, by unraveling the spiral of mats from its outermost end. Thebringing out and recollecting can be done manually or in an automatedfashion. Stacks of pre-connected mats can be stored in advance, whilethe intervals between the mats on one of the ropes can be adjustedon-site as needed. With only one rope, a spiral-type mat arrangement canalso be formed on-site, by successively slipping the rope through theeyes 22 on both opposing (inner and outer) edges of the mats.

Further modifications or variations will be readily contemplated by theskilled person, without departing from the scope of present invention asset out in the appended claims. E.g., although the modules have beendescribed with end grids rigidly connected in pairs, it is alsocontemplated to provide the disks in a more continuous fashion on acentral rope, by sufficiently strongly urging the disks together in alengthwise direction that they do not substantially tilt from theirintended vertical orientation. Although the mats have been shown in thedrawings to be more or less square, it is also contemplated to usetrigonal or hexagonal shapes, both of which enable one to cover a planewithout gaps. Still further, although the absorbent material has beendisclosed as strip-like or chip-like, it is also contemplated that itmay consist of, or comprise, pointed, star-like bodies, e.g. with fourto seven points, or mixtures of the above, as long as the individualbodies maintain sufficiently large interstices between them so thatwater may readily pass through to carry the oil to the absorbent bodies.Even a sufficiently coarsely porous structure is within the scope ofpresent invention. In general, the volume occupied by the bodies amountsto at most 70%, 75%, or 80% of the total inside volume between theenveloping sheets. The air-filled volume inside each of the strips orchips is taken as being an integral part of the strip or chip volume asit is inaccessible to water on account of the material's hydrophobicity.

The invention claimed is:
 1. A fibrous polyolefin oil absorbentmaterial, comprising strips or chips cut from a melt-blown master webmade up of polyolefin fibers, air being present between the fibers,wherein the strips or chips have a length of between 1 and 12 cm, awidth of between 2 and 50 mm, and a thickness extension of between 1 mmand 5 mm.
 2. The fibrous material of claim 1, wherein the polyolefin isselected from polyethylene and polypropylene and mixtures thereof. 3.The fibrous material of claim 1, wherein the master web has an areadensity of between 100 g/m² and 500 g/m².
 4. The fibrous material ofclaim 1, wherein an aspect ratio of the strips or chips is between 5 and100.
 5. The fibrous material of claim 4, wherein the aspect ratio of thestrips or chips is between 8 and
 30. 6. The fibrous material of claim 1,wherein a cross-section of the strips, or a projection of the chips,respectively, has a degree of circularity of between 0.1 and 0.99. 7.The fibrous material of claim 6, wherein the cross-section of thestrips, or the projection of the chips, respectively, has a degree ofcircularity of between 0.2 and 0.95, or between 0.4 and 0.7.
 8. Thefibrous material of claim 1, wherein the longitudinal, width, andthickness extension of the strips is between 7 and 12 cm, between 3 and5 mm, and between 0.5 and 2 mm, respectively.
 9. A floatable modulardevice for absorbing oil from a surface, comprising: a generallydisk-shaped floatable cage tapering towards the periphery of the cage ina peripheral region thereof; and a water-repellent oil absorbentmaterial shaped as strips or chips accommodated in the cage, being theoil absorbent material of claim 1, wherein the cage further comprises atleast one connector element configured for joining plural ones of themodular devices together, to form an articulate oil absorber in whichthe individual cages are oriented in parallel to one another.
 10. Thefloatable modular device of claim 9, wherein there are plural connectorelements each configured to be joined with a corresponding connectorelement of an adjacent, like modular device in a coplanar, edge-onfashion, to form a one- or two-dimensional array, in which array eachmodular device has a generally polygonal disk shape.
 11. The floatablemodular device of claim 10, wherein the plural connector elements areattached lengthwise on an outer peripheral rim of the cage.
 12. Thefloatable modular device of claim 10, wherein one edge of the pluraledges of the polygonal disk-shaped device is formed into an open-endedpouch for accommodating a connecting cable or rod.
 13. The floatablemodular device of claim 10, wherein the plural connector elementsinclude male and female connectors, other than eyes, arranged on rims ofthe device.
 14. The floatable modular device of claim 13, wherein eightconnector elements are distributed around the circumference of aquadrangular device, wherein two of said connector elements are locatedon each side of the device, and wherein the connector elements arelocated in the outer thirds of the respective side.
 15. The floatablemodular device of claim 9, wherein a connecting feature is provided in acentral region of the disk-shaped floatable cage, which connectingfeature fastens opposing faces of the cage to one another.
 16. Thefloatable modular device of claim 15, wherein the connecting featureincludes an opening operable to receive a connecting rod or rope.